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KINSHASA (Reuters) - More than a dozen people have died since the weekend in fighting in southeastern Congo between Bantus and Pygmies, local activists said on Tuesday, in the latest escalation in a bloody three-year ethnic conflict.

The Luba, a Bantu ethnic group, and the Twa, a Pygmy people who inhabit the Great Lakes region, have been in conflict since May 2013 in Democratic Republic of Congo's Katanga region, known for its rich deposits of copper and other metals.

The violence, which has killed hundreds of civilians, has been fueled by social tensions between Bantu villagers and the Twa, a hunting and gathering people who have long been denied access to land and basic services.

David Ngoy Luhaka, a local priest and member of the Diocesan Commission for Justice and Peace, told Reuters that at least 16 people had been killed in fighting since Sunday and many houses were burned near the town of Kabalo, about 1,000 kilometers northwest of Congo's mining hub of Lubumbashi.

Ngoy said it was unclear what sparked this round of violence in the remote area.

Rogatien Kitenge, an advocate for Pygmy rights in the provincial capital of Kalemie, said he had received reports of between 13 and 16 people killed in tit-for-tat attacks between the two groups.

The provincial governor could not immediately be reached for comment.

Experts say security and humanitarian needs in Congo's southeast have largely been neglected as foreign donors and U.N. troops focus on the eastern Kivu provinces and Ituri province further north, which have been ravaged by two decades of deadly conflict.

Heightened political tensions over the delay of a presidential election from next month to April 2018, amid accusations that President Joseph Kabila is trying to cling to power, have also raised fears of an upsurge in localized conflicts over ethnicity and control of natural resources.